1. Field of the Invention
The present invention relates to an optical writing control apparatus and a control method of an optical writing apparatus, and, in particular, to reduction of downtime that occurs for carrying out adjustment of the optical writing apparatus.
2. Description of the Related Art
Recently, computerization is promoted and an image processing apparatus such as a printer and a facsimile machine to be used for outputting computerized information and a scanner or such to be used for computerizing documents may become an indispensable apparatus. Such an image processing apparatus may be, in many cases, a MFP (MultiFunction Peripheral) that is useable as a printer, a facsimile machine, a scanner and a copier by having an imaging function, an image forming function, a communication function and so forth in a single machine.
As an image forming apparatus that is one of such image processing apparatuses and is used to output computerized documents, an image forming apparatus in an electrophotographic type is widely used. The image forming apparatus of the electrophotographic type is such that an electrostatic latent image is drawn on a photosensitive member as a result of the photosensitive member being exposed, a toner image is formed as a result of the electrostatic latent image being developed by using developer such as toner, the toner image is transferred to paper and thus, the image is output as being formed on the paper.
In the image forming apparatus of the electrophotographic type, adjustment is carried out such that the image is formed at a precise position on the paper as a result of timing of exposing the photosensitive member and drawing the electrostatic latent image are made to be coincident with timing of conveying the paper. Further, in an image forming apparatus of a tandem type in which plural photosensitive members are used to form a color image, adjustment of exposure timing between the photosensitive members of respective colors is carried out such that images developed on the photosensitive members for the respective colors are superposed on each other precisely (see Patent Document 1: Japanese Laid-Open Patent Application No. 2008-299311). Hereinafter, these adjustment processes will be generally referred to as position error correction.
As another adjustment operation in the image forming apparatus in the electrophotographic type, there is an operation (hereinafter, referred to as gradation correction) of adjusting a gradation of an image to be formed, i.e., densities of the image. In the gradation correction of an image, plural adjustment patterns having different densities are formed on the photosensitive member of each color, optical sensors are used to read the adjustment patterns, and bias voltages (i.e., development bias) of the photosensitive members (drums) are adjusted so that appropriate gradation is obtained.
In correction of drawing parameters (hereinafter, referred to as drawing parameter correction) such as the position error correction and the gradation correction described above, toner is consumed since the adjustment patterns, i.e., patterns for the adjustment, are formed. Further, the drawing parameter correction may be carried out, for example, at a time of power being turned on in the image forming apparatus, at a time of returning from a power saving mode, or before carrying out forming and outputting an image. In a case where the drawing parameter correction is carried out before forming and outputting, for example, a monochrome image, the drawing parameter correction for the other colors is not necessary. If drawing parameter correction for the other colors is carried out, the toner is consumed as mentioned above, and the toner of the colors other than black is uselessly consumed.
An image forming apparatus has been proposed (see Patent Document 2: Japanese Laid-Open Patent Application No. 2008-151855) as technology to control such useless consumption of color toner in which switching can be made between a monochrome control mode in which gradation correction is carried out only for black toner and a color control mode in which gradation correction is carried out for full color.
In a case of using the technology disclosed by Patent Document 2, both the gradation correction only for black toner and the gradation correction for full color may be carried out within a short span of time when a job for forming and outputting an image of full color is input and the gradation correction for full color is carried out immediately after the gradation correction only for black toner is carried out in the monochrome control mode and an image of monochrome is formed and output.
If so, since the gradation correction for full color includes the gradation correction for black color, the gradation correction for black color is carried out duplicately within the short span of time, and thus, toner is uselessly consumed for drawing the adjustment patterns in the gradation correction. Further, a ratio of an adjustment period of time with respect to a working period of time of the image forming apparatus, i.e., downtime, increases, and thus availability of the image forming apparatus may be degraded. It is noted that such a problem may occur not only on the gradation correction but also on other drawing parameter correction such as the position error correction and so forth.